Small optimization in SpriteAtlas getSprite scaling.
Removed toInt, toFloat util functions. Not necessary in AS3.
Optimized overlap().
removed old onTick & onRender.
Removed Math.floor calls.
Replaced Math.max/min with faster functions.
Replaced Math.round calls with faster version.
Precalculated buffer dimensions halfes and replaced in code to eleminate
several unnecessary divisions in game loop.